Since BJ25 is made for NA, the forged pistons and cyliner with the camshaft and those other parts are made for NA. How much would it cost to change all those stuff to make it turbo-okay? Like forge a piston that does 9:1 and a thicker cylinders like the wrx/sti ones. Anyone have an exact or rough number?

 

Cheapest way is to drop in an STi shortblock. See the STi block SOHC heads thread.

 

Yep...there is a slight amount of moddification to make it fit correctly but its not that bad, not to mention the nice semi closed deck block and better pistons u will be getting....and the torque once u get a nice turbo setup......yummy.